Proportion of Argon in Vapour rising from Liquid Air. 677 



was very marked " boiling " before starting the blower, 

 which largely diminished while the blower was going. 



I am not prepared to give quantitative estimates, which I 

 hope to furnish later ; but all observers to whom I have 

 shown these early results have agreed, that if the a boiling n 

 was not wholly cured, what remained was but a small fraction 

 of that obtained with still air. I have not completed these 

 experiments, which I am still pursuing at the Observatory, 

 but they seem to me to give promise of an improvement of 

 universal interest to observers, which justifies the making of 

 this early announcement. I had hoped to have shown the 

 Association some photographs of the sun taken, first in the 

 ordinary way, and again with the churned air, but the con- 

 dition both of the sun and of the sky of late has prevented 

 my obtaining them. I can, to my regret, only give here a 

 photograph (PI. XVII.) of the images of the artificial double 

 stars as seen through ordinary conditions, as distinguished 

 from those here mentioned, of artificial " good seeing." 



LXXIII. On the Proportion of Argon in the Vapour rising 

 from Liquid Air. By Lord Rayleigh, O.M., F.R.S* 



THE boiling-point of argon being intermediate between 

 those of nitrogen and oxygen, it may be expected that 

 any operations of evaporation and condensation which 

 increase the oxygen relatively to the nitrogen will at the 

 same time increase the argon relatively to the nitrogen and 

 diminish it relatively to the oxygen. In the experiments 

 about to be detailed the gas analysed was that given off from 

 liquid air, either freshly collected, or after standing (with 

 evaporation) for some time — from a day to a week. The 

 analyses were for oxygen and for argon, and were made upon 

 different, though similar, samples. Thus after an analysis 

 of a sample for oxygen by Hempel's method with copper 

 and ammonia, 4 or 5 litres would be collected in a graduated 

 holder, and then the first analysis confirmed on a third 

 sample. In no case, except one to be specified later, was the 

 quantity of gas withdrawn sufficient to disturb sensibly the 

 composition. The liquid was held in De war's vessels, but 

 the evolution of gas from below was always sufficient to keep 

 the mass well mixed. 



The examination for argon was made in a large test-tube 

 inverted over alkali, into which the gas was fed inter- 

 mittently from the holder. The nitrogen was gradually 

 oxidized by the electric discharge from a liuhmkorff coil in 

 connexion with the public supply of alternating current, the 



* Communicated by the Author. 

 Phil. Mag. S. 6. Vol. 5. No. 30. June 1903. 2 Z 



